Originally Posted by Gerry__

The Champ is light so more susceptible to gusts. BUT, with a steady, light breeze, the Champ will not be any more likely to stall turning from upwind to downwind than it would turning on a calm day.

Well, it is.

Go out at fly YOUR champ in a steady 7-10 mph wind and get back to us with your results.

Originally Posted by UNGN

Well, it is.

Go out at fly YOUR champ in a steady 7-10 mph wind and get back to us with your results.

Well read this: https://www.rcgroups.com/forums/show...0#post17415872

Even if you encounter a gust from 7 to 10mph as you turn downwind, the low mass and inertia of the Champs will allow it to quickly regain airspeed. If you could view the Champs ASI (let's pretend it has a tiny, pixie sized one) all you would see is the needle fluctuate.

Maybe you are equating a turn downwind with an automatic reduction of airspeed over the wing with a resultant reduction in lift?

Originally Posted by Gerry__

Well read this: https://www.rcgroups.com/forums/show...0#post17415872

Even if you encounter a gust from 7 to 10mph as you turn downwind, the low mass and inertia of the Champs will allow it to quickly regain airspeed. If you could view the Champs ASI (let's pretend it has a tiny, pixie sized one) all you would see is the needle fluctuate.

Maybe you are equating a turn downwind with an automatic reduction of airspeed over the wing with a resultant reduction in lift?

Please stop trying to equate real plane aerodynamics to a 1.5 OZ plane flying 8 mph in a 7mph wind, because that's apples and oranges.

When you turn downwind, the inside wing can drop and the plane can be pointed at the ground. Since this is the beginner area, beginners should be aware this can happen to them and increase the throttle before turning downwind.

The Parkzone J-3 can use this throttle increase even more than the Champ.

This isn't real aircraft theory, this is micro aircraft reality.

Originally Posted by UNGN

Please stop trying to equate real plane aerodynamics to a 1.5 OZ plane flying 8 mph in a 7mph wind, because that's apples and oranges.

When you turn downwind, the inside wing can drop and the plane can be pointed at the ground. Since this is the beginner area, beginners should be aware this can happen to them and increase the throttle before turning downwind.

The Parkzone J-3 can use this throttle increase even more than the Champ.

This isn't real aircraft theory, this is micro aircraft reality.

You don't know what you're talking about. Did you bother to read the link? You're a typical model flyer who thinks a tailwind reduces airspeed and lift.

During a turn, drag increases, and airspeed decreases, wind or not, that's why increasing power maintains the same airspeed.

Once the Champ is in a block of moving air that we call wind, its aerodynamics are the same as in zero wind. This rule applies to all objects supported by the air/flying. Boeings, balloons and butterflies all conform to this physical imperative.

Due to the low mass and low inertia of the Champ, it will only experience a momentary dip in airspeed if hit by a sudden tailwind gust, which it will quickly regain as the gust pushes against it.

Clearly you have been doing downwind turns in turbulence too near the ground and have rewritten the rules of physics to explain what you see, which is basically you mishandling the Champ.

This is the beginner area, so get your facts right.

Originally Posted by Gerry__

You don't know what you're talking about. Did you bother to read the link? You're a typical model flyer who thinks a tailwind reduces airspeed and lift.

During a turn, drag increases, and airspeed decreases, wind or not, that's why increasing power maintains the same airspeed.

Once the Champ is in a block of moving air that we call wind, its aerodynamics are the same as in zero wind. This rule applies to all objects supported by the air/flying. Boeings, balloons and butterflies all conform to this physical imperative.

Due to the low mass and low inertia of the Champ, it will only experience a momentary dip in airspeed if hit by a sudden tailwind gust, which it will quickly regain as the gust pushes against it.

Clearly you have been doing downwind turns in turbulence too near the ground and have rewritten the rules of physics to explain what you see, which is basically you mishandling the Champ.

This is the beginner area, so get your facts right.

The problem isn't during "headwind" or the "tailwind" but during the transition between the two. The Drag on an aerodynamic body in the plane/vector of the direction of travel IS HIGHER in a Crosswind than Flying straight in or out off the wind, so wind can cause much more drag on the plane in a turn than the same exact plane turning in still air.

Whatever. You are obviouly an expert on a plane you have never flown.

I repeat: Anything you posted about headwinds and tailwinds MAY NOT APPLY to a 8mph plane in a 7mph wind.

I'm not a cut and paste internet expert, like yourself, but do have an an Aeronautical Engineering degree from a major Aiviation University and have 21 years of working at major Aerospace companies and ACTUALLY OWN a Champ and ACTUALLY fly it in wind... so I Kinda know what I'm talking about.

Originally Posted by UNGN

The problem isn't during "headwind" or the "tailwind" but during the transition between the two. The Drag on an aerodynamic body in the directrion of travel IS HIGHER in a Crosswind than Flying straight into the wind, so wind can cause much more drag on the plane in a turn than the same exact plane turning in still air.

Rubbish. And I'm going to make you eat those words. A turning plane has more drag than one flying straight and level. It matters not which way over the ground the air mass is moving, or whether it's moving at all, the amount of drag for any given turn is the same. Headwinds, tailwinds and crosswinds are issues for landing, taking off and navigation only. I suggest you go and do some research, the article I've posted is a good start.

Whatever. You are obviouly an expert on a plane you have never flown.

Own one and have flown it in wind, so there is no mileage for you there.

I repeat: Anything you posted about headwinds and tailwinds MAY NOT APPLY to a 8mph plane in a 7mph wind.

So now you hide behind 'MAY NOT APPLY'. Read the article and debate it with me in my blog, if you dare.

I'm not a cut and paste internet expert, like yourself, but do have an an Aeronautical Engineering degree from a major Aiviation University and have 21 years of working at major Aerospace companies and ACTUALLY OWN a Champ and ACTUALLY fly it in wind... so I Kinda know what I'm talking about.

Yet you can't even spell 'aviation'. You have got yourself confused over the effects of turbulence and have put yourself in a deeply embarrassing position.

Well, I think yer both silly for thinking there's any smooth air within 100 feet of the ground!
None around here, anyway...

Thbthbtbt!


Dave

Originally Posted by Gerry__

Rubbish. And I'm going to make you eat those words. A turning plan has more drag than one flying straight and level. It matters not which way over the ground the air mass is moving, or whether it's moving at all, the amount of drag for any given turn is the same. Headwinds, tailwinds and crosswinds are issues for landing, taking off and navigation only. I suggest you go and do some research, the article I've posted is a good start.

As the plane turns out of a headwind, its the equivalent of a sideslip in calm air and the increased drag on the plane in a sideslip applies.

This sideslip DOES NOT occur in calm air.

People don't fly full sized Champs in 70 mph winds, but if they did, I'm sure they find similar things happening when they turned downwind.

If you own a Champ go fly it in some wind. Fly it into the wind, throttle back to 1/3 throttle and then turn out of the wind.

Try it calm air and see how it behaves differently.

Originally Posted by UNGN

As the plane turns out of a headwind, its the equivalent of a sideslip in calm air and the increased drag on the plane in a sideslip applies.

This sideslip DOES NOT occur in calm air.

Complete rubbish. The only things effected by the crosswind are the ground track and groundspeed. You really need to go and revisit the basics.

People don't fly full sized Champs in 70 mph winds, but if they did, I'm sure they find similar things happening when they turned downwind.

Your problem is that you think a crosswind component has an effect on drag. This is very flawed thinking on your part. Drag increases due to the plane turning and said drag is not increased by the direction of travel over the ground of the air mass the plane is flying in. The increase in drug caused by a turn is the same in still air as it is if the air mass is moving.

If you own a Champ go fly it in some wind. Fly it into the wind, throttle back to 1/3 throttle and then turn out of the wind.

Try it calm air and see how it behaves differently.

You need to read this:

BRIEFING 3 - THE EFFECT OF WIND ON THE AIRCRAFT IN FLIGHT

There is probably more nonsense talked and written on this subject than any other connected with the practical side of flying! In reality, the matter is very simple - it is just that so many people find it hard to accept.

Provided that your flying area is clear of vertical obstructions (houses, trees, hedges, hangers etc.) the wind will blow fairly steadily from a constant direction once the aircraft is above about 50ft. Below this height, and depending on the surface of your flying site and the proximity of obstructions, there will be some turbulence both vertical and lateral.

Once you understand this principle you will see that a turn from an into wind heading to crosswind will appear to be a fairly sharp turn when seen from the ground and a turn from downwind to crosswind will appear to be slow and elongated. You must accept these visual effects for what they are and remember at all times that if you have not altered your throttle setting and the aircraft is at constant height then your airspeed is constant and the aircraft is in no danger of stalling.

Once the aircraft has climbed out of this turbulent level it is, in effect, flying in a steadily-moving block of air. Thus, with a windspeed of 10 mph the block of air in which your aircraft is flying is moving downwind at a speed of 10 mph. So, your aircraft which flies at a speed of, say 20 mph will appear to be doing only 10 mph when flying into the wind (flying speed less windspeed) and 30 mph when flying downwind (flying speed plus windspeed). In point of fact your aircraft knows nothing about the windspeed at all and is flying at a steady 20 mph all the time!

You will often hear people say that their aircraft tends to climb when turning into wind and dive when turning downwind. What is really happening, of course, is that they are subconsciously trying to compensate for the apparent variation in speed and themselves causing the aircraft to climb and dive.

One major point to remember - don’t try to keep your apparent speed constant or you will find that you will have your aircraft at full throttle when going into wind and stalling when it goes downwind.

If you find all this difficult to visualise, try to imagine yourself piloting a model boat from the bank of a fast-flowing river. In this situation you will find that you can understand the problems outlined above.

When flying in a wind of any strength you will find that your model can be carried away from you very quickly when it is travelling downwind. It is essential not to let it go too far. If you do, not only do you stand a good chance of losing control because you just can’t see the aircraft properly, but it is a long and slow slog back to your position against the full strength of the wind. There is another major factor - if your engine stops it will be difficult or impossible to glide the aircraft back to your position if it is too far downwind.

So always try to keep your aircraft upwind of your position as much as possible. By doing so you will save yourself from falling into some very difficult situations.

Originally Posted by CNY_Dave

Well, I think yer both silly for thinking there's any smooth air within 100 feet of the ground!

I'm saying that he is observing the effects of turbulence and attributing these turbulence induced effects to some imagined effects of a crosswind component.

Amazing that someone so highly qualified can be so wrong.

Put a plane in a wind tunnel. Turn the plane 20 degrees to the direction of airflow and watch the drag in the direction of airflow double.

That's what's happening when you initially turn out of a headwind.

The Champ has mild tip stall characteristics and the wing may only dip, but the J-3 Cub will fall out of the sky, if you don't increase the power before turning.

Originally Posted by UNGN

Put a plane in a wind tunnel. Turn the plane 20 degrees to the direction of airflow and watch the drag in the direction of airflow double.

That's what's happening when you initially turn out of a headwind.

Oh dear, oh dear! This plane, in this wind tunnel, it wouldn't be attached to the wind tunnel in any way, would it?

A turning plane has more drag than when it's flying straight. A crosswind does not create more drag for a plane as it turns.

You are wrong, horribly, horribly wrong. Run it by some of your colleagues at work, why don't you?

Headwinds and crosswinds are landing, take off and navigation consideration only and do not affect a plane's aerodynamic performance.

You still haven't bothered to read any of the stuff I have provided for you, have you?

Originally Posted by Gerry__

Oh dear, oh dear! This plane, in this wind tunnel, it wouldn't be attached to the wind tunnel in any way, would it?

A turning plane has more drag than when it's flying straight. A crosswind does not create more drag for a plane as it turns.

You are wrong, horribly, horribly wrong. Run it by some of your colleagues at work, why don't you?

Headwinds and crosswinds are landing, take off and navigation consideration only and do not affect a plane's aerodynamic performance.

You still haven't bothered to read any of the stuff I have provided for you, have you?

I used the wind tunnel example to explain the throry behind what I'm trying to explain to you, but it doesn't appear you are getting it.

A plane flying directly into a headwind has lower drag than a plane flying into the same headwind with a 5 degree sideslip, correct?

When you turn out of a headwind in a slab sided highwing drag goes up much more than if are making the same turn in calm air.

The reasons for this is the increase in the effective frontal area of the plane (Because the sides of the plane are now part of the frontal area) and the Increase in the drag coef of the plane angled to the airflow.

On a highwing, slab sided plane, this drag increase could be 2X the drag of a plane flying directly into a headwind at some point in the turn and in the direction of the travel of the plane it would be the Drag X COS of the angle to the airflow, which at 20 degrees of turn is still 90%.

On a real plane that isn't flying in winds that are 150% of stall speed, you may not see this as much... but if you did, you would.

Gentlemen,

A very interesting discussion; one that has been repeated numerous times on various threads and in various forums. While the laws of Newtonian Physics always apply (when we are not dealing with things on the microscopic level or nearing the speed of light) two things are important to remember. One is that objects with a very low mass, and consequently a low inertia, will react in an exagerated manner compared to their heavier, larger counterparts when an outside force is applied. The other is that our perception, while standing on the ground, is not that same as it would be if we were in the first person, sitting inside the plane.

As far as the discussion between Gerry and UNGN, Gerry has presented the far more accurate information. When you turn a plane, no matter what plane it is, it will loose lift. There are several ways to compansate for this loss, but if you took absolutely no action, you would find that the plane will be at a lower altitude when it exits the turn then when it entered. If you do this in calm conditions the loss of altitude occurs over a considerable amount of "land". However, if you do the same thing when you have a strong headwind, the loss will appear to be compressed over a short amount of land and will make the plane appear to be about to stall. When you compare flight in calm air to flight in STEADY wind, there is absolutely no difference as far as the plane is concerned until you are either taking off or landing. However, steady wind is very hard to find when you are flying parkflyers, particularly Micros. Once the wind starts to change in speed, direction or both, all kinds of strange forces start to act upon the plane and it can exhibit very strange and unnerving flight characteristics.

For example, take the PZ J3Cub or SuperDecathlon, neither of which is a Micro, but are on the small side of Parkflyers. They are both fairly notorious for being hard to fly in wind. Take them out on a windy day and try to fly them at 50 - 100 ft. They will be quite a handfull and will exhibit all sorts of strange behavior. Now take them up to 800 ft. (yes, they will appear as a tiny little spec) but they will exhibit completely normal flight characteristics within their moving air mass.

Originally Posted by UNGN

I used the wind tunnel example to explain the throry behind what I'm trying to explain to you, but it doesn't appear you are getting it.

A plane flying directly into a headwind has lower drag than a plane flying into the same headwind with a 5 degree sideslip, correct?

When you turn out of a headwind in a slab sided highwing drag goes up much more than if are making the same turn in calm air.

The reasons for this is the increase in the effective frontal area of the plane (Because the sides of the plane are now part of the frontal area) and the Increase in the drag coef of the plane angled to the airflow.

On a highwing, slab sided plane, this drag increase could be 2X the drag of a plane flying directly into a headwind at some point in the turn and in the direction of the travel of the plane it would be the Drag X COS of the angle to the airflow, which at 20 degrees of turn is still 90%.

On a real plane that isn't flying in winds that are 150% of stall speed, you may not see this as much... but if you did, you would.

For a plane flying in a mass of air, there is no headwind, or crosswind or tailwind. These components only come into consideration for landing, take off and navigation.

As far as the plane is concerned, it only has airspeed, that is speed in relation to the air molecules it is flying through. That the mass of air that the plane is fly through is moving across the ground is of absolutely no aerodynamic importance.

For the plane, there is only airspeed. There is no increase in drag when turning in an air mass that is moving in relation to the ground. And you still haven't bothered to read the articles I posted.

Now let's deal with this bit in detail:

A plane flying directly into a headwind has lower drag than a plane flying into the same headwind with a 5 degree sideslip, correct?

You are confusing headwind with airspeed. Read the article by Jim Davis. You are really embarrassing yourself.